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'Orbital molecules' - self-organised states for orbitronics

Final Report Summary - ORBITMOL ('Orbital molecules' - self-organised states for orbitronics)

Orbital molecules (OMs) are clusters of weakly bonded metal ions in a ceramic material such as a metal oxide. This project has explored large OMs (consisting of more than 2 metal ions) looking at chemical tuning of orbital molecule self-organisation, discovery of novel orbital molecule orders in frustrated networks, and investigations of magnetic 3-atom OMs known as trimerons in the mineral magnetite, the original magnetic material. New understanding of magnetite has been one of the major discoveries. A Dutch scientist Verwey discovered in 1939 that the mineral magnetite undergoes a complex change of structure and physical properties on cooling to low temperatures (below 125 K). The low temperature state had been a mystery until the presence of trimeron OMs was discovered in 2012. In this project we have shown that OMs are also present in a disordered way above the Verwey transition, so all the uses of magnetite at ambient temperature (e.g. by magnetically sensing bacteria, in compasses for navigation in past times) have made use of the OMs in magnetite. We have also shown that disordered OMs persist at high temperatures in other materials, and that OM formation can drive separation of a material into two components (like a mixture of oil and water). OMs are a fascinating new area of quantum properties of solids, and may help to underpin future electronic technologies based on the creation and manipulation of orbital states.